Most pressure regulator designs are based on the concept of an adjustable orifice that is controlled by using an adjustable spring bias to provide a pressure set-point. The principle difference in previous designs of these devices is centered on the method by which the spring bias is applied.
The most common technique for biasing a spring is to apply force directly to the spring by means of an adjusting screw. This technique requires that the device must overcome the force of the spring, as well as the system pressure, and it is the least efficient. A typical control device consists of a pin and seat which, working with a bias spring, provides a controlled orifice.
For low pressure, the down side of using this technique is relatively small, and the complexity of the valve is minimal. For high pressure, the force of adjustment becomes more problematical and thus, other techniques to artificially bias the spring are used. In some cases, the seat is adjusted independently relative to the control pin, which artificially biases the springs. In other cases, the pin is biased relative to the spring by changing its relationship to the seat.
There are a number of pressure regulators that employ a moving seat conceived to overcome some of the shortcomings of the previous technology. The major improvement introduced here is to change the method of biasing the piston spring set. In previous patented technologies, either the springs were adjusted from an external source, or a moving seat was employed to achieve the same result In both cases, it was necessary to overcome the system pressure in order to make an adjustment, which resulted in high torque loads needing to be applied for any adjusting screws